1. Field of The Invention
The invention relates to a process for converting hydrogen sulfide into sulfur and hydrogen. More specifically, hydrogen sulfide gas is reacted with a quinone dissolved in an aqueous solvent containing a sulfur complexing agent, yielding sulfur and the corresponding hydroquinone which is then converted back to the quinone while releasing hydrogen gas.
2. Description of Related Art
Many processes related to the petroleum industry generate gaseous by-products containing hydrogen sulfide, by itself or in a mixture with other gases, such as carbon dioxide. U.S. Pat. No. 4,581,128 to Plummer and Zimmerman discloses a process for desulfurizing a hydrocarbon feedstock having a relatively high sulfur content by contacting the feedstock with hydrogen gas in the presence of a catalyst to obtain a hydrocarbon product having a relatively low sulfur content. The hydrogen sulfide gas by-product produced therewith is treated with a quinone dissolved in a polar organic solvent to obtain a sulfur product and a hydroquinone. The hydroquinone is regenerated by contacting it with air in the presence of a catalyst. The resulting quinone is recycled back to the absorption reaction while hydrogen peroxide produced as a by-product is reduced to oxygen and water. The oxygen is used to partially oxidize a hydrocarbon fuel which generates hydrogen gas and hydrogen gas is recycled to the initial desulfurization step. U.S. Pat. No. 4,592,905 to Plummer and Beazley discloses a process for contacting and reacting hydrogen sulfide gas with an anthraquinone dissolved in a polar organic solvent to yield sulfur and the corresponding anthrahydroquinone. Sulfur precipitates from the solution and is recovered as a product. The remaining anthrahydroquinone solution is fed to a dehydrogenation reactor where it is thermally or catalytically regenerated to produce the initial anthraquinone form in solution and hydrogen gas. The anthraquinone solution is recycled back to the hydrogen reactor and the hydrogen is recovered as a product. U.S. Pat. No. 3,913,966 to Vaughan discloses a process for reacting hydrogen sulfide with an anthraquinone in an organic solvent in the presence of an organic base catalyst to produce elemental sulfur and an anthrahydroquinone. The sulfur is recovered and the anthrahydroquinone is oxidized to yield the starting anthraquinone and hydrogen peroxide.
The above cited patents require the use of polar organic solvents. Polar organic solvents generally require that health, safety and environmental protection precautions be taken to prevent harm to personnel or to the environment. Therefore a need exists for a process to convert hydrogen sulfide gas to sulfur via a quinone system which does not utilize polar organic solvents thus eliminating potential problems associated with the use of such solvents.
It is therefore an object of this invention to provide a process for the conversion of hydrogen sulfide gas to sulfur and hydrogen gas which uses an aqueous solvent rather than a polar organic solvent.